As a content filling bottle, which accommodates liquid contents such as a drink therein, for example, a bottle (PET bottle) made by blow forming a polyethylene-terephthalate material has been known.
With this type of bottle, when an opening of the bottle is hermetically sealed with a cap and the contents of the bottle are then cooled, a decrease in the volume of the contents or the like reduces the pressure in the bottle. This may deform a body part of the bottle, making the appearance of the bottle unfavorable.
Therefore, a plurality of flexible panels are formed on the body part to evenly absorb the deformation accompanying the internal pressure reduction caused by the cooling of the contents after filling (see, for example, Japanese Patent Laid-Open No. 6-72423). However, the provision of such panels complicates the shape of the bottle, thus increasing the material cost for the bottle.
Consequently, in a known device, a portion of the bottom part of the bottle can be inverted between a concave shape and a convex shape so that the liquid contents are filled into the bottle with the inversion part projecting outwardly from the bottom and so that after the bottle opening is sealed with the cap, the inversion part is recessed inwardly into the bottle (National Publication of International Patent Application No. 2006-501109).
Thus, with the bottle described in National Publication of International Patent Application No. 2006-501109, prior to filling of the liquid contents into the bottle, the inversion part of the bottom part of the bottle is pressed out so as to project outwardly from the body part.
Then, liquid contents are filled into the interior of the bottle with the inversion part of the bottom part projecting outwardly from the body part. The opening of the bottle is then sealed with the cap.
Thereafter, the outwardly projecting inversion part of the bottom part of the bottle is pressed up toward the interior of the bottle so as to be recessed inwardly into the bottle. Thus, the pressure inside the bottle increases. As a result, even when a pressure reduction results from, for example, the cooling of the liquid contents, the pressure reduction is canceled by the above-described pressure increase, preventing the body part of the container from being subjected to reduced pressure deformation.
In this manner, the inversion part, which can be inverted between the concave and convex shapes, is formed in the bottom part of the bottle and inverted in the stage of produce of the content filling bottle. This eliminates the need to provide the body part of the bottle with a panel that evenly absorbs such deformation as described above. This in turn enables an increase in the degree of freedom of bottle design and a reduction in the material costs of the bottle.
However, with the bottle that prevents the reduced pressure deformation of the body part by the concave and convex inversion of the bottom part of the bottle, the inversion part of the bottom part of the bottle needs to be projected outwardly from the body part before filling of the contents. This makes the bottom part of the bottle unstable and thus makes it difficult to transport the bottle in a self-standing state.
Therefore, a cylindrical auxiliary tool having a stable ground portion to assist in making the bottle self-standing is installed in the bottom part of the bottle so that the inversion part of the bottom part can be accommodated in the auxiliary tool. Then, regardless of whether the inversion part is in the concave or convex state, the bottle can be stood upright via the auxiliary tool. As a result, stable self-standing transportation can be carried out.
However, for example, if heated contents are filled into the bottle (what is called hot filling), then before the filling of the contents, the bottle is turned upside down and washed with washing water. However, when the bottle with the auxiliary tool installed therein is turned upside down for washing, the washing water stuck on the auxiliary tool flows down to the opening of the bottle. This makes the bottle unsanitary.
If contents at the ordinary temperature are filled into the bottle (what is called aseptic filling), the bottle is used of which an inner surface and an outer surface are sterilized and the filling operation is performed in a sterile state. In this case, to remain installed in the bottle, the auxiliary tool needs to be subjected to a sterilization treatment or the like. This increases the number of operation man-hours, thereby reducing efficiency.